Friction lock assembly and retaining ring for wellhead

ABSTRACT

A locking assembly and a retaining ring for retaining the locking assembly within a bore of a wellhead component are provided. In one embodiment, a system includes an inner component disposed within a bore of a wellhead component and a locking assembly disposed within the bore to secure the inner component within the bore. The locking assembly includes a lock ring that extends into a recess in a wall of the bore of the wellhead component and an actuator radially disposed between the inner component and the lock ring. The system also includes a retaining ring that limits movement of the actuator along the inner component and maintains the actuator between the inner component and the lock ring to retain the lock ring within the recess. The actuator and the retaining ring have mating tapered surfaces that inhibit movement of the actuator out of engagement with the lock ring.

BACKGROUND

This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the presently described embodiments. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present embodiments. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.

In order to meet consumer and industrial demand for natural resources, companies often invest significant amounts of time and money in finding and extracting oil, natural gas, and other subterranean resources from the earth. Particularly, once a desired subterranean resource such as oil or natural gas is discovered, drilling and production systems are often employed to access and extract the resource. These systems may be located onshore or offshore depending on the location of a desired resource.

Further, such systems generally include wellhead assemblies mounted on wells through which resources are accessed or extracted. Such wellhead assemblies can include a wide variety of components, such as various spools, casings, valves, pumps, fluid conduits, and the like, that control drilling or extraction operations. In many instances, casings are coupled to wellheads via hangers installed in bores of the wellheads. These hangers and other components within the bores can be retained in various ways, and sealing packoffs can be used to seal annular spaces within the bores.

SUMMARY

Certain aspects of some embodiments disclosed herein are set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of certain forms the invention might take and that these aspects are not intended to limit the scope of the invention. Indeed, the invention may encompass a variety of aspects that may not be set forth below.

Embodiments of the present disclosure generally relate to locking assemblies that can be used to secure components in bores and to retaining rings for retaining the locking assemblies in locked positions within the bores. In one embodiment, a locking assembly is used to secure a hanger in a wellhead bore. The locking assembly includes a lock ring and an actuator that is moved to a locked position to drive the lock ring into engagement with a mating surface to secure the hanger in the bore. A retaining ring is positioned over the locking assembly to inhibit unsetting of the actuator from the locked position. In at least some instances, the retaining ring and the actuator have mating tapered surfaces that cooperate to oppose movement of the actuator out of the locked position.

Various refinements of the features noted above may exist in relation to various aspects of the present embodiments. Further features may also be incorporated in these various aspects as well. These refinements and additional features may exist individually or in any combination. For instance, various features discussed below in relation to one or more of the illustrated embodiments may be incorporated into any of the above-described aspects of the present disclosure alone or in any combination. Again, the brief summary presented above is intended only to familiarize the reader with certain aspects and contexts of some embodiments without limitation to the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of certain embodiments will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:

FIG. 1 is a block diagram of a system having a wellhead with various components installed at a well in accordance with one embodiment of the present disclosure;

FIG. 2 is an exploded view of a wellhead hanger apparatus including a locking assembly and a retaining ring in accordance with one embodiment;

FIGS. 3 and 4 are detail views of the wellhead hanger apparatus of FIG. 2 installed within a wellhead component in accordance with one embodiment;

FIGS. 5 and 6 show a wellhead hanger apparatus having a retaining ring with inner and outer sleeves installed in the wellhead component in accordance with one embodiment; and

FIGS. 7 and 8 depict a wellhead hanger apparatus having a locking assembly with an actuator having an inner sleeve and an outer ring installed in the wellhead component in accordance with one embodiment.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

Specific embodiments of the present disclosure are described below. In an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.

When introducing elements of various embodiments, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Moreover, any use of “top,” “bottom,” “above,” “below,” other directional terms, and variations of these terms is made for convenience, but does not require any particular orientation of the components.

Turning now to the present figures, a system 10 is illustrated in FIG. 1 by way of example. The system 10 is a production system that facilitates extraction of a resource, such as oil or gas, from a reservoir 12 through a well 14. A wellhead 16 is installed on the well (e.g., attached to the top of casing and tubing strings in the well). As shown here, the wellhead 16 includes at least one tubing head 18 and casing head 20. The wellhead 16 also includes various inner components 22 inside the wellhead, such as annular plugs and casing and tubing hangers. The components 22 inside the wellhead 16 can also include packoffs for inhibiting fluid leakage within the wellhead 16 and locking assemblies for securing wellhead hangers (e.g., casing and tubing hangers), plugs, or other inner components within the wellhead 16. Certain examples of such locking assemblies are described in greater detail below. In at least some embodiments, the locking assemblies are constructed for use in high and low temperatures and for high pressure within the wellhead 16 exceeding 20 ksi. The depicted system 10 also includes a tree 24 (e.g., a Christmas tree) to facilitate resource production from the well 14.

By way of example, components of an apparatus 40 with a wellhead hanger 48 and a friction locking assembly 50 for securing the wellhead hanger 48 within a bore are illustrated in FIGS. 2-4 in accordance with one embodiment. Though shown here with the wellhead hanger 48, it is noted that the locking assembly 50 could instead be used to secure plugs or other components within a bore of a wellhead apparatus. The depicted locking assembly 50 includes a lock ring 54 and an actuator 56, which is shown in the present figures in the form of an annular sleeve and may also be referred to as an energizing ring. In addition to the wellhead hanger 48 and the locking assembly 50, the apparatus 40 is also shown in FIGS. 2-4 as including a retaining ring 52 and a load ring 58, which may also be referred to as a bearing ring. The components of the apparatus 40 can be formed of metal or of any other suitable material.

In FIGS. 3 and 4, the apparatus 40 is shown disposed within a bore of a wellhead component 42, such as a tubing head or casing head, with the locking assembly 50 installed between an inner component (here the wellhead hanger 48) and the wellhead component 42. As depicted, the hanger 48 is positioned on a landing shoulder within the bore of the wellhead component 42. The landing shoulder can be formed as an integral part of the wellhead component 42, i.e., as a tapered edge of the bore wall, or can be a separate component installed within the bore. In at least some instances, the hanger 48 can be threaded onto (or otherwise coupled to) a plug or some other component.

As depicted in FIGS. 3 and 4, the lock ring 54 and the actuator 56 are positioned about a neck 60 of the hanger 48. The lock ring 54 includes ridges 62 along its outer circumference. The bore wall of the wellhead component 42 has mating recesses 64 for receiving the ridges 62 of the lock ring 54. In the presently depicted embodiment, the load ring 58 is positioned between the lock ring 54 and a shoulder of the hanger 48, and includes a recess 70 for receiving a distal end 72 of the actuator 56.

The actuator 56 can be moved axially along the neck 60 to lock and unlock the assembly 50. More specifically, the actuator 56 can be wedged between the neck 60 and the lock ring 54 to cause the lock ring 54 to expand into engagement with the recesses 64, and the actuator 56 can be at least partially withdrawn from between the neck 60 and the lock ring 54 to allow the lock ring 54 to contract and disengage from the recesses 64. In its unlocked state, the locking assembly 50 can be moved (e.g., carried by the hanger 48) axially within the bore of the wellhead component 42, such as during installation of the hanger 48 in the bore. Once the locking assembly 50 and the hanger 48 are axially positioned at their intended locations within the bore (i.e., with the hanger 48 on the landing shoulder of the wellhead component 42 and the lock ring 54 adjacent to the recesses 64), the actuator 56 can be pushed axially downward along the neck 60 toward the landing shoulder so that the actuator 56 is radially positioned between the lock ring 54 and the neck 60 of the hanger 48.

Examples of this locked state are depicted in FIGS. 3 and 4. It will be appreciated that the axial position of the actuator 56 when in its locked state may vary in different implementations. In some instances, such variation may be attributable to height and diametrical dimension tolerance stack-ups or deflections in the system. This variation is generally depicted in the present drawings, in which FIG. 3 depicts the actuator 56 in a lower locked position and FIG. 4 depicts the actuator 56 in a higher locked position due to differences in tolerance stack-ups and deflections.

A tapered interface 68 of the lock ring 54 and the actuator 56 causes the lock ring 54 to expand radially as the actuator 56 is driven between the lock ring 54 and the neck 60. To facilitate this radial expansion, the lock ring 54 is provided as a split ring (e.g., a C-ring) in at least some embodiments. The expansion of the lock ring 54 results in the movement of the ridges 62 into the recesses 64, which inhibits axial movement of the hanger 48 within the bore 42.

Once run into the bore of the wellhead component 42, the locking assembly 50 of at least some embodiments can be set using only axial motion to secure the hanger 48 (or some other component) inside the bore. Unlike other locking assemblies that require rotation of an element (such as a threaded ring) within bores to set the locking assemblies and secure components within the bores, the presently depicted locking assembly can be set by axially driving (e.g., with a running tool) the actuator 56 between the lock ring 54 and the hanger 48 to cause the lock ring 54 to engage the recesses 64. Rotation of components within a bore can increase the risk of damage to the bore and other components. By axially setting the locking assembly 50, such an increased risk of damage from rotation can be avoided. Axial setting also allows the use of less complicated tooling in installing the locking assembly 50, which can reduce installation time and expense. The locking assembly 50 can also be unlocked via axial force, such as by engaging an upper end of the actuator 56 with a tool and pulling the actuator 56 away from the load ring 58 to allow the lock ring 54 to relax and retract from the recesses 64.

Further, when in its locked position, the locking assembly 50 provides a preload on the hanger 48. This preload in some instances can be equal to the expected loading on the hanger 48 from wellbore fluids in the wellhead during operation. As depicted in FIGS. 3 and 4, the ridges 62 and recesses 64 have mating tapered edges. As the lock ring 54 is driven into engagement with the recesses 64 by the actuator 56, the mating engagement of the upper tapered surfaces of the ridges 62 and the recesses 64 cause the lock ring 54 to be driven downward and to apply a compression force on the load ring 58, thus applying a preload on the hanger 48. It will be appreciated that the amount of preload depends on the geometries of the lock ring 54, the load ring 58, and the recesses 64, which can vary between different embodiments.

In some prior art designs, locking assemblies in wellheads are retained by providing devices, such as springs, above the locking assemblies to load against the locking assemblies and inhibit axial movement. In other prior art designs, threaded connections are used to retain locking assemblies at a desired location. But in contrast to such prior art designs, in at least some embodiments of the present disclosure friction alone is used to retain a locking assembly 50 in the locked position without the need for rotation or other retention mechanisms.

For example, the actuator 56 of the locking assembly 50 depicted in FIGS. 3 and 4 is installed on the neck 60 of the hanger 48 with an interference fit. More specifically, after the actuator 56 is driven between the lock ring 54 and the neck 60 to cause the lock ring 54 to engage the wellhead component 42, the actuator 56 can be held in its locked position by friction between the neck 60 and the actuator 56 (along an interface 66 between these two components) and friction between the actuator 56 and the lock ring 54 (along the tapered interface 68).

As noted above, stack-up tolerances, deflections, or other factors can cause variation in the height of the actuator 56 (i.e., its position along the neck 60) when set in the locked position. The steep taper between the actuator 56 and the lock ring 54 at the tapered interface 68 generally compounds this variation. Because of the uncertainty of the height position of the actuator 56 in a given application, verification of the proper setting of the locking assembly 50 can be difficult. Consequently, in at least some embodiments the hanger apparatus 40 includes a retaining ring 52 that accommodates variation in the locking position of the actuator 56.

As shown in FIGS. 3 and 4, the retaining ring 52 engages the actuator 56 along a tapered interface 80. The direction of taper of the interface 80 is the reverse of that of interface 68. That is, the actuator 56 includes a first tapered surface at interface 68 that tapers toward the lower end of the actuator 56, as well as a second tapered surface at interface 80 that tapers in the opposite direction toward the upper end of the actuator 56. This second tapered surface of the actuator 56 is provided along an outer edge of an exterior flange of the actuator 56 in the embodiment illustrated in FIGS. 3 and 4, but is provided in different manners in other embodiments.

While the actuator 56 may be primarily retained through friction along interfaces 66 and 68 (i.e., friction with the neck 60 and the lock ring 54), vibration, shock loads, or other forces could cause movement of the actuator 56 along the neck 60 away from the locked position. A secondary retention mechanism, such as the retaining ring 52, can be used to prevent inadvertent unsetting of the actuator 56 if friction with the neck 60 and the lock ring 54 is insufficient to hold the actuator 56 in the locked position. In such an instance, upward movement of the actuator 56 along the neck 60 would increase hoop deflection in the retaining ring 52, allowing the stiffness of the retaining ring 52 to create an increasing retention load on the actuator 56 that inhibits movement of the actuator 56 out of engagement with the lock ring 54. That is, given the tapered surfaces of the interface 80, the retention load applied by the retaining ring 52 continues to increase as the actuator 56 moves upward. In FIGS. 3 and 4, upward movement of the actuator 56 would increase outward hoop deflection in the retaining ring 52, though the arrangement of the retaining ring 52 and the actuator 56 could be reversed at the tapered interface 80 such that the upward movement of the actuator 56 would instead increase inward hoop deflection of the retaining ring 52.

Another example of the retaining ring 52 is depicted in FIGS. 5 and 6, which show the actuator 56 in its locked state at lower and upper axial positions, such as described above with respect to FIGS. 3 and 4. In this additional embodiment, the retaining ring 52 is provided as a mechanism including an outer sleeve 86 and an inner sleeve 88, with the tapered interface 80 provided between the inner sleeve 88 and the actuator 56. The inner sleeve 88 can be provided as a bending ring that deflects in response to applied force from the actuator 56. In this arrangement, upward movement of the actuator 56 would be resisted by increased hoop deflection of the inner sleeve 88 caused by the movement of the actuator 56. The inner sleeve 88 can be pinned or threaded to the outer sleeve 86, or can be connected to the outer sleeve 86 in any other suitable manner.

An additional example of the actuator 56 in its locked state at lower and upper axial positions is shown in FIGS. 7 and 8. In this depicted embodiment, the actuator 56 includes a main body or inner sleeve 94 and an outer ring 96 (e.g., a C-ring or a solid ring) that engages the retaining ring 52. The tapered interface 80 is provided between the outer ring 96 and the retaining ring 52. Moreover, in this embodiment, the tapered interface 80 causes inward hoop deflection of the outer ring 96 (and an increasing retention load) in response to upward movement of the actuator 56. The outer ring 96 is carried on a shoulder of the inner sleeve 94 in at least some instances. Additionally, rather than including a separate load ring 58, the hanger 48 in FIGS. 7 and 8 is shown as having an integral load ring 58. But the load ring 58 could be provided as a separate load ring in the embodiment depicted in FIGS. 7 and 8. Likewise, instead of having a separate load ring 58, the embodiments depicted in FIGS. 2-6 could instead include a load ring 58 that is integral with the hanger 48.

As will be appreciated, each of the various locking assemblies 50 described above can be run into the bore of a wellhead component 42 and, once positioned, the actuator 56 can be moved to a locked position to drive the lock ring 54 into engagement with the wellhead component 42 and secure the wellhead hanger 48 or another component within the bore. In some instances, the locking assembly 50 is run into the bore with the hanger 48. The retaining ring 52 can also be lowered into the bore with the locking assembly 50, or after the locking assembly 50 is run into the bore, and positioned so that the mating surfaces of the tapered interface 80 oppose movement of the actuator 56 along the hanger 48 toward an unlocked position.

A packoff can be installed in the bore above the locking assembly 50. In the presently depicted embodiments, the retaining ring 52 is provided as part of such a packoff (i.e., a packoff landing ring) and the retaining ring 52 is lowered into the bore as part of the packoff. By omitting a separate retention device between a packoff and the locking assembly 50, the packoff can be installed closer to (e.g., in contact with) the locking assembly 50, which enables the use of a shorter wellhead assembly. But the retaining ring 52 could be provided independent of a packoff in other embodiments.

While the aspects of the present disclosure may be susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and have been described in detail herein. But it should be understood that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the following appended claims. 

1. A system comprising: a wellhead component having a bore; an inner component disposed within the bore of the wellhead component; a locking assembly disposed within the bore between the inner component and the wellhead component to secure the inner component within the bore of the wellhead component, the locking assembly including: a lock ring that extends into a recess in a wall of the bore of the wellhead component; and an actuator radially disposed between the inner component and the lock ring; and a retaining ring positioned within the bore of the wellhead component so as to limit movement of the actuator along the inner component and maintain the actuator between the inner component and the lock ring to retain the lock ring within the recess, wherein the actuator and the retaining ring have mating tapered surfaces that inhibit movement of the actuator out of engagement with the lock ring.
 2. The system of claim 1, wherein the actuator includes a flange, and the flange and the retaining ring have the mating tapered surfaces that inhibit movement of the actuator out of engagement with the lock ring.
 3. The system of claim 1, wherein the retaining ring is a multi-piece mechanism including an outer sleeve and an inner sleeve, and the actuator and the inner sleeve of the retaining ring have the mating tapered surfaces that inhibit movement of the actuator out of engagement with the lock ring.
 4. The system of claim 1, wherein the actuator includes an inner sleeve radially disposed between the inner component and the lock ring and an outer ring positioned about the inner sleeve, and the outer ring and the retaining ring have the mating tapered surfaces that inhibit movement of the actuator out of engagement with the lock ring.
 5. The system of claim 4, wherein the outer ring is carried on a shoulder of the inner sleeve.
 6. The system of claim 1, wherein the retaining ring is a landing ring of a packoff.
 7. The system of claim 1, wherein the retaining ring is positioned within the bore on the lock ring of the locking assembly.
 8. The system of claim 1, wherein the actuator has an interference fit with the inner component to inhibit movement of the actuator between the lock ring and the inner component.
 9. The system of claim 1, wherein the inner component is a wellhead hanger.
 10. The system of claim 1, comprising a bearing ring between the lock ring and a shoulder of the inner component.
 11. A system comprising: a locking assembly to secure a device in a bore of a wellhead component, the locking assembly including: a lock ring; and an actuator configured to be radially disposed between the device and the lock ring such that the actuator can be moved axially in a first direction along the device to drive the lock ring radially outward to a locked position in which the lock ring secures the device within the bore of the wellhead component; and a retaining ring, wherein the retaining ring and the actuator having mating tapered surfaces that, when installed in the bore of the wellhead component, limit axial movement of the actuator in second direction, opposite the first direction, along the device so as to facilitate retention of the actuator in engagement with the lock ring in the locked position.
 12. The system of claim 11, wherein the mating tapered surfaces limit axial movement of the actuator in the second direction by cooperating with one another so as to apply an increasing retention load on the actuator as the actuator moves in the second direction.
 13. The system of claim 11, wherein the lock ring and the actuator have additional mating tapered surfaces, and the mating tapered surface of the actuator and the additional mating tapered surface of the actuator are tapered in opposite directions.
 14. The system of claim 11, wherein the actuator includes an outer ring carried on an inner sleeve, and the outer ring and the retaining ring have the mating tapered surfaces such that engagement of the mating tapered surfaces causes the outer ring to contract inwardly about the inner sleeve in response to axial movement of the actuator in the second direction.
 15. The system of claim 11, comprising the device, wherein the device includes a wellhead hanger.
 16. A method comprising: running a locking assembly into a bore of a wellhead component, the locking assembly including a lock ring and an actuator; driving the lock ring into engagement with the wellhead component by moving the actuator between the lock ring and an additional wellhead component to a locked position so as to secure the additional wellhead component within the bore; lowering a retaining ring into the bore of the wellhead component; and positioning the retaining ring along the actuator such that a tapered interface between the retaining ring and the actuator opposes movement of the actuator along the additional wellhead component toward an unlocked position.
 17. The method of claim 16, wherein driving the lock ring into engagement with the wellhead component by moving the actuator between the lock ring and the additional wellhead component to the locked position so as to secure the additional wellhead component within the bore includes wedging the actuator between the lock ring and the additional wellhead component so as to secure the additional wellhead component within the bore via an interference fit of the additional wellhead component with the actuator.
 18. The method of claim 16, comprising running the additional wellhead component into the bore with the locking assembly.
 19. The method of claim 18, wherein running the additional wellhead component into the bore includes running a wellhead hanger carrying the locking assembly into the bore.
 20. The method of claim 16, wherein lowering the retaining ring into the bore includes lowering a packoff having the retaining ring into the bore. 